The present application relates to systems and methods for performing an inspection of turbine rotor blades. More particularly, but not by way of limitation, the present application relates to a technique for inspecting turbine rotor blade surfaces for any irregularities, defects, or other types of flaws on the blade surface.
It will be appreciated that combustion or gas turbine engines (“gas turbines”) include a compressor, combustor, and turbine. The compressor and turbine sections generally include rows of blades that are axially stacked in stages. Each stage includes a row of circumferentially-spaced stator blades, which are fixed, and a row of the rotor blades, which rotate about a central turbine axis. In operation, generally, the compressor rotor blades rotate about the central axis, and, acting in concert with the stator blades, compress a flow of air. The supply of compressed air then is used in the combustor to combust a supply of fuel. The resulting flow of hot expanding gases from the combustion, i.e., the working fluid, is expanded through the turbine section of the engine. The flow of working fluid through the turbine induces the rotor blades to rotate. The rotor blades are connected to a central shaft such that the rotation of the rotor blades rotates the shaft. The shaft may further be connection to the rotor blades within the compressor. The energy contained in the fuel, thus, may be converted into the mechanical energy of the rotating shaft, which, for example, may be used to rotate the rotor blades of the compressor, such that the supply of compressed air needed for combustion is produced, as well as, the coils of a generator so to generate electrical power.
In the gas turbine industry, advancing technology is required to meet necessary power output requirements in a cost-effective manner. During operation of a gas turbine, the blades of both the compressor and turbine are subject to damage from a variety of sources, including creep from long-term exposure to heat, cracks and stress from fatigue, and nicking in the blade surface from foreign particles of dust and other materials present in the air flowing through the gas turbine. Such incidents of damage introduce deformations in the surface of blades, concomitantly reducing the overall efficiency and increasing the fuel consumption needed for the turbine system to operate at a desired output.
To address the issue of blade surface damage, the turbine engine is occasionally removed from operation, disassembled, and inspected to ensure that the blades are properly functioning. A major component of this inspection typically includes a visual inventory of the surfaces of each blade, looking for signs of damage, including deformations, tears, rips, holes, cracks, and any other defects. This inspection is performed manually for each surface of each blade, introducing a high amount of error and variability in the process of maintaining blades. Moreover, for the inspection process to yield meaningful results, it requires an enormous investment in both time and labor resources. Overall, the arduous conventional inspection process, combined with the probability of errors during such inspections, collectively contribute to more frequent and longer engine downtimes and an increased risk of failure events. As will be appreciated, these issues add significant cost to the operation and maintenance of gas turbines. Systems and methods that improve aspects of the inspection process relating to gas turbine blades would be demanded in the marketplace.